Geometry. Find the angle.
2010-12-20 2:21 am
圖片參考：http://imgcld.yimg.com/8/n/HA04776011/o/701012190089413873429330.jpg
Square ABCD is rotated through 15 degree anticlockwise about A to AB'C'D'. Find∠CC'B'.
回答 (2)
2010-12-20 3:07 am
✔ 最佳答案
∠CAB=45 (diagonal of square) ∠C'AB=45+15=60 (C is rotated 15 about A)
Consider the triangle ACC',
∠C'AC=∠C'AB-∠CAB=60-45=15
triangle ACC' is isoceles (since AC=AC')
∠C'CA=(180-∠C'AC)/2=(180-15)/2=82.5(∠ sum of triangle)
∠CC'B=∠C'CA+∠ACB=82.5+45=127.5
2010-12-19 19:51:01 補充：
sorry...
∠CC'B'
=∠CC'A-∠AC'B'
=82.5-45
=37.5
I have calculated ∠C'CB..
2010-12-20 3:36 am
∠CC'B = ∠C'CA - ∠ACB
收錄日期: 2021-04-21 22:17:28
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